A model train wonderland hidden beneath Gare de l'Est station.

This massive library holds what was once the largest book collection in the world.

At this barrel organ museum, history and live concert keep Dutch street organ culture alive.

A uniquely preserved neo-Gothic church that is now home to a collection of art and woodcarvings.

Some 80,000 Delft Blue tiles line the inside of this Amsterdam walkway.

This Netherlands museum holds a gloriously mechanical collection of ornate musical automata.

A Jenga-style cylindrical tower of books that appears to go on forever.

An encyclopedic collection of mammal penises.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Walk through Czech history in Prague's largest graveyard.

Legends surround an ancient tree trunk riddled with nails for good luck.

Explore this medieval cathedral by trying to spot all the malevolent monsters hiding in its beautifully colored windows.

There has been an astronomical clock on this spot since the 14th century.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

After decades of research and rumors, Little Zion Church was proven to be his final resting place.

This towering church is home to a world-famous organ and a treasure trove of medieval art.

Terrifically morbid cemetary and site of famous Paracelsus' grave.

The amazing wonder cabinets of a very rich Austrian archbishop.

These 12th-century catacombs carved into a mountainside were a place of mysticism and Christian hermitages.

A melancholy jester sits on the grave of a famous 20th-century ballet dancer and choreographer.

Stripes of human ashes cover a back lawn in the most sought-after burial grounds in Paris.

A short distance from the Eiffel Tower is the final resting place of several of the city’s more well-known and interesting characters.

A simple plaque on the facade is the only reminder that the treaty ending the American Revolution was signed inside.

A magical, macabre wax museum, beloved by locals, uses real artifacts to depict an assassination from the French Revolution.